The present invention relates to a tool for screwing a screw having two threaded shanks separated by an intermediate portion provided for receiving screwing means.
Such a tool has many surgical applications, in particular in thoracoscopy and spinal osteosynthesis . . . , for placing screwed implants in position.
Screws are known which have two threaded shanks of different pitches in the extension of each other and separated by an intermediate engaging portion for screwing. Screws of this type are disclosed in particular in the document EP-A-0 612 507. The intermediate portion between the two threaded portions may be spherical, conical, or hexagonal, etc. In the case where this portion is spherical or conical, it has two lateral notches to allow the engagement of a screwing tool. These notches are difficult for the surgeon to find during the surgical intervention, constitute fracture initiators, and require a special machining station, which results in additional cost when manufacturing the screw.
Further, the engaging portion formed by a hexagonal screwing shape, considerably increases the overall size of the screw, which constitutes a further drawback.
An object of the invention is therefore to provide a screwing tool which is easily used by the surgeon in the course of the intervention and is of great strength.